IRBIL, Iraq — With Iraqi forces surrounding Mosul for an imminent assault, residents were hoarding food and furtively scrawling resistance slogans on walls, the city’s Islamic State rulers were building tunnels and staying out of sight of drones, and Iraqi helicopters were dumping leaflets predicting that the end of the terrorist reign is near.
Interviews with roughly three dozen people from Mosul, including refugees who managed to sneak out in recent weeks and residents reached by contraband cellphones in the city, portrayed a pressure-cooker-like atmosphere. On Monday morning, Prime Minister Haider al-Abadi, speaking on state TV, gave his forces the order to assault Mosul, setting in motion a campaign to take back Iraq’s second-largest city from the Islamic State. After dark on Sunday evening, armored vehicles on flatbed trucks were seen moving west from Irbil, the capital of the autonomous Kurdish region, and near Mosul, the sounds of artillery fire could be heard.
The stakes are high for Mosul, a Sunni stronghold long disaffected from Iraq’s Shiite leaders. The city is also the largest ever ruled by the extremists and, as their designated capital, a potent symbol of their claim to statehood.
Just getting out of Mosul has become difficult and dangerous: Those who are caught face million-dinar fines, unless they are former members of the Iraqi police or army, in which case the punishment is beheading.
While the civilians described stockpiling food in basement hiding places, the jihadis were said to be frantically making military preparations within Mosul, temporarily fleeing the streets — most likely to an extensive tunnel network below — at the first signs of an airstrike, according to the new accounts.
Some of Mosul’s remaining 1 million or more residents have grown bolder in showing resistance against the Islamic State force ruling the city — numbering 3,000 to 4,500 fighters, the U.S. military estimates. Graffiti and other displays of dissidence against the Islamic State have become more common there in recent weeks, as have executions when the vandals have been caught.
Early this month, 58 people were executed for their role in a plot to overturn the Islamic State that was led by an aide of the group’s leader, Abu Bakr al-Baghdadi, Reuters reported.
When fewer than 1,000 Islamic State fighters forced about 60,000 Iraqi army and police defenders to abandon Mosul in June 2014, many among its Sunni population cheered their arrival. They saw the militants as fellow Sunnis who would end corruption and abuse at the hands of the Shiite-dominated Iraqi government and security services.
But much of that local good will has dissipated after more than two years of harsh rule by the militants, a mix of Iraqis and Syrians with a grab bag of foreign fighters.
Mosul residents have chafed under social codes banning smoking and calling for splashing acid on body tattoos, summary executions of perceived opponents, whippings of those who missed prayers or trimmed their beards, and destroying “un-Islamic” historical monuments.
“Anyone who has accepted Daesh before? They’ve changed their minds now,” said Azhar Mahmoud, a former Education Ministry official who recently fled his home village near Mosul, and who initially accepted rule by the Islamic State, also known as ISIS, ISIL or Daesh.
In addition, there have been recent reports of at least some underground resistance within the city, if mostly symbolic. Photos and oral accounts abound of the Arabic letter M scrawled on walls — standing for moqawama, or resistance. The Islamic State beheaded two men in front of one such slogan, and posted a video of the killings.
Another execution video identified the victims, punished for internet use, as members of the resistance group Suraya Rimah, according to the group’s leader, Omar Fadil al-Alaf, who is based in Irbil.
“People are just waiting for liberation so they can fulfill their promises to take revenge on Daesh and kill them,” al-Alaf said.
Compounding the militants’ problems with the population has been a growing economic crisis, according to U.S. officials. In recent months, the Islamic State has lost control of oil fields near Raqqa in Syria and Qaiyara in Iraq, and trade with Islamic State-held parts of Syria has been choked off because of the group’s military reversals.
Electricity, once plentiful before Kurdish forces took back the Mosul Dam from militant control, is now typically available in the city for only a couple of hours a day, residents say. Some areas lack running water, with residents forced to use personal generators to pump water from wells.
Schools have not opened at all this year, absent funding and teachers willing to work for nothing.
The local economic crisis has hit the militants as well, with reports that they have cut the pay for their fighters to less than $100 a month, from $400 in 2014, said Abu Bakr Kanan, a former leader of the Sunni religious affairs office in Mosul, who said he was in regular touch with residents there.
Many of the residents contacted describe the militants as conducting a high-profile recruiting drive among 14- to 40-year-old males, depicting enlistment as a religious duty, but with apparently decreasing success.
A car mechanic who left the city just over two weeks ago, and asked not to be identified because he still had relatives there, said that on his final Friday in Mosul he attended prayers at which a prominent Islamic State imam harangued the worshippers about volunteering but seemingly won no one over.
The militants’ security preparations have been directed not only at the city’s borders — particularly toward the south and east where Iraqi forces, allied militias and Kurdish peshmerga fighters are arrayed — but also internally. Traffic on secondary roads in the city has been banned, and house-to-house searches — for weapons and any signs of organized resistance — have been carried out in many neighborhoods.
Last month, a YouTube video surfaced of Suraya Rimah fighters appealing to residents of Mosul to kill their Islamic State rulers when the offensive begins.
Resistance groups in the city — at least five claim to have a presence — say they have concentrated on assassinating individuals, said Abdullah Abu Ahmed, who described himself as a leader of an anti-Islamic State brigade in Mosul called The Resistance. He was reached by telephone through intermediaries.
“All Mosul people, whenever they have the chance to fight and kill ISIS terrorists, they do so,” he said. He cited a recent attack on a jewelry market in which two members of the Islamic State were killed.
Over the past few weeks, coalition airstrikes have begun more intensively targeting the suspected homes of senior Islamic State figures in Mosul. Residents said those senior militants, many of whom had relatively high public profiles in the city, had become conspicuous by their absence on the streets.
There have also been a notable number of desertions from the Islamic State. Kurdish officials say they have found 300 suspected ISIS deserters, or potential infiltrators, in recent months. Most were caught among the refugees escaping from Islamic State-held territory who have arrived at the Kurdish-run Dibaga Camp, the main site for refugees, south of Irbil, said Ardalan Mohiadin, who is in charge of the camp’s reception center.
Dibaga Camp now has 43,000 refugees from Mosul and other Islamic State strongholds, with about 11,000 arriving in September alone, Mohiadin said.
Despite months of preparation for a much larger wave of refugees from the city, aid officials warn that it is unlikely to be nearly enough once the fighting intensifies.
“The United Nations is deeply concerned that in a worst-case scenario, the operation in Mosul could be the most complex and largest in the world in 2016, and we fear as many as 1 million civilians may be forced to flee their homes,” said Lise Grande, the U.N.’s humanitarian coordinator for Iraq.
Airstrikes on the militants in Mosul have led many of them to move in among civilian residents, the locals say.
A woman who arrived at Dibaga Camp recently said her family had been forced to take in a Chechen ISIS fighter, and shortly afterward an airstrike hit the home, killing the militant but also two members of the family. The woman’s 9-year-old daughter was trapped under a collapsed wall.
The girl survived and is with her mother in the camp now.
Nearly all of the Mosul residents contacted spoke on condition of anonymity for fear of ISIS retaliation. Even most refugees did not want to be identified because they still had relatives in Mosul.
“We are suffering from so many problems, we feel like the living dead,” said a woman who identified herself only by the initials S.A.
In addition to U.S. air support, President Barack Obama this month approved an additional 615 U.S. troops to aid the Mosul offensive by providing intelligence and logistical assistance. That brings the U.S. forces in Iraq to more than 5,000.
Some in Mosul described how militants had begun going house to house to collect used tires that could be set on fire to generate smoke screens.
“We expect everything,” said Sabah al-Numan, the spokesman for the Iraqi Counterterrorism Force. “We know this is the last station for ISIS — there is nowhere else for them to go. We have to prepare for a very tough fight.”